LETTER
Total Synthesis of Prelaureatin
1495
(6) (a) Fukuzawa, A.; Aye, M.; Takasugi, Y.; Nakamura, M.;
Tamura, M.; Murai, A. Chem. Lett. 1994, 2307.
(b) Ishihara, J.; Shimada, Y.; Kanoh, N.; Takasugi, Y.;
Fukuzawa, A.; Murai, A. Tetrahedron 1997, 53, 8371.
(7) For the first total syntheses of 1 and 4, see: Crimmins, M. T.;
Tabet, E. A. J. Am. Chem. Soc. 2000, 122, 5473.
(8) For recent reviews on olefin metathesis, see: (a) Grubbs, R.
H.; Miller, S. J.; Fu, G. C. Acc. Chem. Res. 1995, 28, 446.
(b) Schuster, M.; Blechert, S. Angew. Chem., Int. Ed. Engl.
1997, 36, 2067; Angew. Chem. 1997, 109, 2124.
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(d) Armstrong, S. K. J. Chem. Soc., Perkin Trans. 1 1998,
371. (e) Blechert, S. Pure Appl. Chem. 1999, 71, 1393.
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Chem. Soc., Perkin Trans. 1 1998, 4175.
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Org. Chem. 1996, 61, 5716. (b) Uenishi, J.; Kawahama, R.;
Yonemitsu, O.; Tsuji, J. J. Org. Chem. 1998, 63, 8965. (c)
See, also: Fujiwara, K.; Awakura, D.; Tsunashima, M.;
Nakamura, A.; Honma, T.; Murai, A. J. Org. Chem. 1999,
64, 2616.
(11) Another approach to cyclize a triene precursor into a
medium-sized cyclic ether by RCM has been reported,
where the modest selectivity has been observed: Crimmins,
M. T.; Emmitte, K. A.; Choy, A. L. Tetrahedron 2002, 58,
1817.
the resulting aldehyde 25 was subjected to Wittig reaction
to afford 6 in 44% total yield with 43% recovery of 24.
RCM reactions of 6 using two Grubbs’ catalysts 2718 and
2819 gave the interesting results (Table in Scheme 3).
While the use of catalyst 27 afforded cyclohexene 26 ex-
clusively (75%), less-reactive catalyst 28 led to produc-
tion of the desired oxocene 5 (56%, with 13% recovery of
6) rather than 26 (6%) under the same conditions. In both
cases, no oxepane product was observed.
Finally, the enyne part of 1 was constructed by a modifi-
cation of Uenishi’s protocol.10 Selective hydrogenolysis
of dibromoalkene part of 5 led to a formation of 29 in 82%
yield. Although bromide 29 was inactive to Sonogashira
coupling reaction20 with ethynyltrimethylsilane, desilylat-
ed 30 could be coupled as expected under the same condi-
tions to produce 31 in 46% yield with 52% recovery of 30.
Removal of TMS with TBAF in wet THF produced 1 in
quantitative yield.1,6b Spectral data of synthetic 1 were
identical with those of natural prelaureatin.1 Thus, total
synthesis of 1 was achieved in 26 steps from galactose
pentaacetate.
In conclusion, total synthesis of prelaureatin, isolated
from red alga Laurencia nipponica, has been achieved
through a process including stereoselective introduction
of two allyl groups starting from galactose pentaacetate,
cleavage of the hexose ring, and transformation of an
acyclic triene into an oxocene by selective ring-closing
metathesis.
(12) Giannis, A.; Sandhoff, K. Tetrahedron Lett. 1985, 26, 1479.
(13) (a) Omura, K.; Swern, D. Tetrahedron 1978, 34, 1651.
(b) Mancuso, A. J.; Huang, S.-L.; Swern, D. J. Org. Chem.
1978, 43, 2480. (c) Mancuso, A. J.; Swern, D. Synthesis
1981, 165.
(14) Henry, K. J.; Grieco, P. A. Jr.; Jagoe, C. T. J. Tetrahedron
Lett. 1992, 33, 1817.
(15) (a) Shimizu, T.; Hiranuma, S.; Nakata, T. Tetrahedron Lett.
1996, 37, 6145. (b) Shimizu, T.; Ohzeki, T.; Hiramoto, K.;
Hori, N.; Nakata, T. Synthesis 1999, 1373.
(16) (a) Hooz, J.; Gilani, S. S. H. Can. J. Chem. 1968, 46, 86.
(b) Murai, A.; Murase, H.; Matsue, H.; Masamune, T.
Tetrahedron Lett. 1977, 2507. (c) Tsushima, K.; Murai, A.
Tetrahedron Lett. 1992, 33, 4345.
Acknowledgement
The authors are grateful to Mr. Kenji Watanabe and Dr. Eri Fukushi
(GC-MS & NMR Laboratory, Graduate School of Agriculture,
Hokkaido University) for the measurements of mass spectra.
(17) (a) Schmidt, S. P.; Brooks, D. W. Tetrahedron Lett. 1987,
28, 767. (b) Brats, M.; Bullock, W. H.; Overman, L. E.;
Takemoto, T. J. Am. Chem. Soc. 1995, 117, 5958. (c) See,
also: Fujiwara, K.; Kobayashi, M.; Awakura, D.; Murai, A.
Synlett 2000, 1187.
(18) Scholl, M.; Ding, S.; Lee, C. W.; Grubbs, R. H. Org. Lett.
1999, 1, 953.
(19) Fu, G. C.; Nguyen, S. T.; Grubbs, R. H. J. Am. Chem. Soc.
1993, 115, 9856.
References
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Synlett 2002, No. 9, 1493–1495 ISSN 0936-5214 © Thieme Stuttgart · New York